[Maxo]

I was under the impression that one didn't need to set backlash if everything, especially the pinion shims, from the donor transmission were used. That's what I did when I swapped out my front differential earlier this year.
If you're planning on rebuilding the differential, I've read that putting lithium grease on gears, bolting up the diff and spinning the gears, then unbolt and check where they were touching is one way to check backlash.